WO2021056654A1 - 一种实现煤体孔裂隙动态渗流过程可视化的方法 - Google Patents

一种实现煤体孔裂隙动态渗流过程可视化的方法 Download PDF

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WO2021056654A1
WO2021056654A1 PCT/CN2019/112995 CN2019112995W WO2021056654A1 WO 2021056654 A1 WO2021056654 A1 WO 2021056654A1 CN 2019112995 W CN2019112995 W CN 2019112995W WO 2021056654 A1 WO2021056654 A1 WO 2021056654A1
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coal
coal sample
sample
pore
visualization
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PCT/CN2019/112995
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English (en)
French (fr)
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王刚
韩冬阳
程卫民
秦相杰
刘志远
孙路路
刘义鑫
倪冠华
刘震
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山东科技大学
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
    • G01N23/02—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material
    • G01N23/04—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material
    • G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N24/00—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects
    • G01N24/08—Investigating or analyzing materials by the use of nuclear magnetic resonance, electron paramagnetic resonance or other spin effects by using nuclear magnetic resonance
    • G01N24/081—Making measurements of geologic samples, e.g. measurements of moisture, pH, porosity, permeability, tortuosity or viscosity

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  • the invention relates to the technical field of coal seam water injection seepage, in particular to a method for realizing the visualization of the dynamic seepage process of coal pores and fissures.
  • Coal seam water injection as a means of artificial rock formation intervention, can actively promote the solution of coal mine actual production problems such as gas outburst, impact ground pressure, spontaneous combustion and coal softening.
  • the seepage effect of coal seam water injection is affected by the characteristics of its own pore-fracture structure.
  • a correct understanding of the pore-fracture structure and seepage distribution characteristics of coal is an important basis for studying coal seam porosity, spatial structure, seepage characteristics and coalbed methane recoverability.
  • mercury intrusion method mercury intrusion method can test the mesoporous and macroporous structure, but the test process will cause irreversible damage to the coal sample; nitrogen adsorption method, nitrogen adsorption The method only tests the characteristics of micropores, and the above methods have their own defects.
  • the traditional nuclear magnetic resonance test can obtain the development status of pores and fractures, connectivity and pore size distribution, but it is difficult to visually observe the true flow of water in the pores and fractures.
  • Three-dimensional reconstruction of CT images obtained by CT scanning can simulate the dynamic process of fluid seepage in coal pores and cracks, but due to the idealization and complexity of numerical simulation, it is difficult to accurately characterize water under real conditions by using CT scanning technology.
  • Flow conditions in pores and cracks At present, there is no mature non-destructive dynamic detection technology to realize the visual characterization and analysis of the dynamic process of coal pores and fissures. Only by realizing the whole process of visualization of the dynamic process of seepage, can we clearly understand the flow state of the fluid in the pore and fracture structure of the coal body.
  • the present invention provides a way to realize the visualization of dynamic seepage process of coal pores and fissures.
  • the specific technical scheme is as follows.
  • a method for realizing the visualization of the dynamic seepage process in the pores and fissures of coal bodies the steps include:
  • Step A Make a coal sample, and perform a CT scan on the coal sample to obtain a CT scan image
  • Step B Dry the coal sample to a constant weight, and divide the position of the saturated water soaked coal sample, and perform vacuum saturated water treatment step by step according to the position;
  • Step C Perform nuclear magnetic resonance experiments on the coal sample, intercept multiple sections of the coal sample at equal intervals from any direction, and determine the moisture distribution in multiple directions and multiple sections;
  • Step D Observe and divide each position of the saturated water-soaked coal sample, and combine the moisture distribution of each section to obtain a three-dimensional T 2 map and a water-bearing signal map;
  • Step E Observe the pore and fissure structure of the coal sample, and analyze the dynamic process of seepage.
  • the coal sample in step A is a cylindrical sample
  • the scanning voltage, scanning power and field of view during CT scanning are based on X-ray stability, coal sample size, coal sample X-ray attenuation score and The exposure time is determined; the coal sample rotates at a fixed speed during the CT scan, and the detector captures the X-rays passing through the coal sample, and stores the CT scan image in the form of electrical signals.
  • step B specifically involves vacuuming the coal sample at room temperature for 24 hours, then putting it in a drying oven to dry to a constant weight, and then weighing the dry weight of the coal sample.
  • dividing the position of the saturated water-soaked coal sample is specifically to determine the position of the saturated water-soaked coal sample at intervals of 8-15 mm, starting from the end of the coal sample according to the saturated water
  • the position of the soaked coal sample is subjected to water saturation treatment step by step.
  • step C a multi-dimensional nuclear magnetic resonance analyzer is used to perform the nuclear magnetic resonance experiment, and the multi-layer circular cross section and the rectangular cross section are cut at a distance of 5 mm.
  • step D the multi-dimensional nuclear magnetic resonance analyzer also measures the relaxation distribution and relaxation time of the coal sample to produce a three-dimensional T 2 map.
  • the beneficial effect of the present invention is that a CT scanner is used to scan the coal sample to obtain a CT scan image with various coal seam pore and fissure structures, and then the same coal sample is scanned by a multi-dimensional nuclear magnetic resonance analyzer to obtain a three-dimensional T 2 map And water-bearing signal map; combined with the layered imaging technology of the NMR equipment, the section of the coal and rock mass is intercepted from any direction of the coal pillar to obtain the moisture distribution of any layer, so that the NMR can not be observed due to the limited accuracy of the intercepted section
  • the obtained coal body pore and fissure structure is compared with the nuclear magnetic resonance spectrum, and then the dynamic process of coal body pore and fissure seepage is visualized throughout the whole process, and the whole process of coal body dynamic seepage is visualized.
  • Figure 1 is a schematic diagram of a coal sample
  • Figure 2 is a schematic diagram of the location of the coal sample wetted by saturated water
  • Figure 3 is a schematic diagram of the cross-section selection of the coal sample
  • Example 4 is a three-dimensional T 2 spectrum and a water-containing signal diagram in Example 2;
  • Example 5 is a schematic diagram of the pore and fissure structure of the coal sample in Example 2.
  • micro-fractures pores-fractures
  • the existence of micro-fractures (pores-fractures) in the coal body increases the seepage channels with less resistance in the reservoir and affects the permeability of the reservoir.
  • the changes in the local pressure field and flow field in the pores and fissures cause the fluid to pass preferentially.
  • Micro-fracture seepage, the basic characteristics of pores and fractures (such as pore structure, connectivity, etc.) and fluid parameters (such as fluid viscosity, density, etc.) that are difficult to obtain through existing experimental methods.
  • the invention provides a non-destructive dynamic detection technology, which realizes the visual characterization and analysis of the dynamic process of the seepage flow in the coal pores and fissures.
  • a method for realizing the visualization of the dynamic seepage process of coal pores and fissures using the Xradia 510 Versa 3D X-ray microscope CT scanner with two-stage magnification technology to scan the coal sample to obtain CT pictures with the pore and fissure structure of each coal seam;
  • a MacroMR12-100H-GS multi-dimensional nuclear magnetic resonance analyzer was used to scan the same coal sample to obtain a three-dimensional T 2 map and water-bearing signal map.
  • the cross section of the coal and rock mass is intercepted from any direction of the coal pillar to obtain the moisture distribution of any layer.
  • the coal sample is a cylindrical sample, and the size of the sample is preferably During CT scanning, the scanning voltage, scanning power and field of view are determined according to X-ray stability, coal sample size, coal sample X-ray attenuation fraction and exposure time; during CT scanning, the coal sample rotates at a fixed speed.
  • the detector captures X-rays passing through the coal sample, and stores CT scan images in the form of electrical signals.
  • the drying of the coal sample is specifically to vacuum the coal sample at room temperature for 24 hours, then put it in a drying oven to dry to a constant weight, and then weigh the dry weight of the coal sample.
  • the drying temperature can be set to 60 °C.
  • Divide the position of the saturated water-soaked coal sample specifically to determine the position of the saturated water-soaked coal sample every 8-15mm. In addition, it can also be divided into more positions with a smaller interval to improve Accuracy of the test; from one end of the coal sample to the saturated water-soaked coal sample position, the immersion saturation treatment is carried out step by step, which can be carried out in the order from bottom to top. After each position is saturated, it will be lowered.
  • Field NMR measurement is specifically to vacuum the coal sample at room temperature for 24 hours, then put it in a drying oven to dry to a constant weight, and then weigh the dry weight of the coal sample.
  • the drying temperature can be set to 60 °C.
  • Divide the position of the saturated water-soaked coal sample specifically to determine the position of the saturated water-
  • the nuclear magnetic resonance experiment was carried out on the coal sample, and the multi-layer cross-sections of the coal sample were cut at equal intervals from any direction to determine the moisture distribution in multiple directions and multiple cross-sections.
  • the MacroMR12-100H-GS multi-dimensional nuclear magnetic resonance analyzer is used for nuclear magnetic resonance experiments.
  • the interval of 5mm can be set to intercept multi-layer circular cross-sections and rectangular cross-sections.
  • the multi-dimensional nuclear magnetic resonance analyzer also measures the relaxation distribution and relaxation time of the coal sample to produce a three-dimensional T 2 map.
  • the above method first scans the coal sample with a CT scanner to obtain CT scan images with pores and cracks in each coal seam, and then scans the same coal sample with a multi-dimensional nuclear magnetic resonance analyzer to obtain a three-dimensional T 2 map and water-bearing signal map Combining with the layered imaging technology of the nuclear magnetic resonance equipment, the cross section of the coal and rock mass is intercepted from any direction of the coal pillar to obtain the moisture distribution of any layer, so that the coal can not be observed by the nuclear magnetic resonance due to the limited accuracy of the intercepted section
  • the pore and fissure structure is compared with the nuclear magnetic resonance spectrum, and then the dynamic process of coal pore and fissure seepage can be visualized throughout the whole process, and the whole process of coal dynamic seepage can be visualized.
  • the method based on CT scanning and nuclear magnetic resonance technology to study the dynamic process of coal pore and fissure structure can make up for the limitations of other methods, and only the use of nuclear magnetic resonance T 2 atlas cannot study the deficiencies of the dynamic seepage process, and realize the dynamic seepage of coal pores and fissures.
  • the process visualization method uses the Xradia510Versa3D X-ray microscope CT scanner with two-stage magnification technology to scan the coal sample to obtain CT scan pictures with the fracture structure of each coal seam.
  • a MacroMR12-150H-I nuclear magnetic resonance imaging analyzer was used to scan the same coal sample to obtain a three-dimensional T 2 map and a water-bearing signal map.
  • the cross section of the coal and rock mass is intercepted from any direction of the coal pillar to obtain the moisture distribution of any layer.
  • observe the pore and fissure structure of the coal body that cannot be observed by the NMR due to the limited accuracy of the intercepted section and compare it with the NMR T 2 map and the moisture distribution map, and then visually analyze the seepage of the coal body pore and fissure in the whole process. Dynamic Process.
  • Step A Before the CT scan test, make the Tangkou coal sample into a size of The coal pillars are shown in Figure 1.
  • the experimental conditions are 6W and the field of view is 12.5 ⁇ 12.5mm 2.
  • the coal sample rotates at a constant scanning speed. X-rays pass through the sample and are captured by the detector, and stored in the form of electrical signals to form a CT image.
  • Step B Vacuum the coal sample at room temperature for 24 hours, put it in a drying oven at 60° C. to dry to a constant weight, and then weigh the dry weight of the sample to remove residual moisture in the sample.
  • the position of the saturated water-soaked coal sample is divided every 10mm, and according to the divided position of the soaked coal sample, 5 vacuum saturated water treatments are performed one by one from the low position to the high position, as shown in Figure 2. As shown, after the saturation of each position is completed, a low-field NMR test is performed.
  • Step C Use MacroMR12-100H-GS multi-dimensional nuclear magnetic resonance analyzer to test the coal sample after CT scanning.
  • the hydrogen test probe coil is a 25mm self-shielded coil, the magnet strength is 0.3T, and the magnet temperature is 32 ⁇ 0.01°C.
  • the coal sample can be divided longitudinally at different positions according to the actual distribution of pores and cracks. By observing the locations and cross sections of different coal samples soaked in saturated water, the water distribution of the coal seam water flowing into the pores can be observed in real time.
  • Step D By observing the location of different coal samples soaked in saturated water and the moisture distribution of different cross-sections, combined with the three-dimensional T 2 map (height, relaxation time, signal amount) and water-bearing signal map obtained from the nuclear magnetic resonance experiment From this, the pore and fissure structure and the location where water can flow can be judged, and the dynamic process of water flowing into the pore can be observed in real time.
  • the schematic diagram of the water distribution and the layered water-bearing signal of any layer is shown in Figure 4.
  • Step E Due to the limited accuracy of the MRI layered imaging technology, the pores and fissures between each coal seam less than 1 mm cannot be observed. Combined with the coal body pore and fissure structure diagram after CT scanning, as shown in Figure 5, the defects of the coal body pore and fissure structure that cannot be observed due to the limited accuracy of the NMR intercepted section can be compensated, and the dynamic process of seepage can be analyzed in the whole process.

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Abstract

一种实现煤体孔裂隙动态渗流过程可视化的方法，包括以下步骤：对煤样试件进行CT扫描得到具有孔裂隙结构的CT扫描图像；干燥煤样试件至恒重，划分饱和水浸湿煤样的位置，按照划分进行抽真空饱和水处理，煤样试件进行核磁共振实验，得到三维T 2图谱和含水信号图；利用核磁共振分层成像技术，从任意方向截取固定间距的各层截面，得到煤样试件任意层面孔裂隙水分分布图，并分析动态渗流的过程；结合含水信号图分析CT扫描图像中的孔裂隙结构，实现了煤体动态渗流全程的可视化，从而可以更好的认识流体在煤体孔裂隙结构的流动过程，并为研究煤层渗流规律提供了便利。

Description

一种实现煤体孔裂隙动态渗流过程可视化的方法 技术领域
本发明涉及煤层注水渗流技术领域，尤其是一种实现煤体孔裂隙动态渗流过程可视化的方法。
背景技术
煤层注水作为人工岩层干预手段，可以积极推动解决瓦斯突出、冲击地面压力、自燃和煤体软化等煤矿实际生产问题。煤层注水渗流效果受到自身孔隙-裂隙结构特征的影响，正确认识煤体孔隙-裂隙结构及渗流分布特征，是研究煤层孔隙性、空间结构、渗流特征以及煤层气可采性的重要依据。
目前，研究煤体孔裂隙结构的方法有许多，具体有：压汞法，压汞法可以测试中孔和大孔结构，但测试过程会对煤样造成不可逆的破坏；氮气吸附法，氮气吸附法仅测试微孔孔隙特征，上述方法都有各自的缺陷。
传统的核磁共振试验可以得到孔隙、裂隙发育状况，连通性及孔径分布等，但很难可视化地观测水在孔裂隙中的真实流动过程。通过CT扫描获得CT图片对其进行三维重建，虽能模拟流体在煤体孔裂隙中渗流的动态过程，但由于数值模拟的理想化和复杂性，利用CT扫描技术也很难准确表征真实条件下水在孔裂隙中的流动情况。目前还没有一种成熟的无损动态检测技术，以实现对煤体孔裂隙渗流动态过程可视化的表征和分析。只有实现全程可视化的渗流动态过程，才能清楚地认识流体在在煤体孔裂隙结构的流动状态。
由于上述研究方法并不能观测真实条件下煤体的动态渗流过程，且均存在一定局限性。因此，现有的研究技术有待于更进一步的改善和发展，需要一种研究煤体结构动态渗流全程可视化的方法，为进一步的研究煤层渗流规律提供方便。
发明概述
技术问题
问题的解决方案
技术解决方案
为了实现煤体动态渗流全程的可视化，更好的认识流体在煤体孔裂隙结构的流动过程，并为研究煤层渗流规律提供了便利，本发明提供了一种实现煤体孔裂隙动态渗流过程可视化的方法，具体技术方案如下。
一种实现煤体孔裂隙动态渗流过程可视化的方法，步骤包括：
步骤A.制作煤样试件，对煤样试件进行CT扫描得到CT扫描图像；
步骤B.干燥煤样试件至恒重，并划分饱和水浸湿煤样试件的位置，按照位置划分逐段进行抽真空饱和水处理；
步骤C.对煤样试件进行核磁共振实验，从任意方向对煤样试件等间距截取多层截面，确定多个方向及多个截面的水分分布；
步骤D.观测划分饱和水浸湿煤样试件的各个位置，结合各个截面的水分分布，得到三维T 2图谱和含水信号图；
步骤E.观测煤样试件的孔裂隙结构，分析渗流动态过程。
进一步的，步骤A中煤样试件为圆柱体试件，CT扫描过程中扫描电压、扫描功率和视场大小根据X射线稳定性、煤样试件尺寸、煤样试件X射线衰减分数和曝光时间来确定；CT扫描时煤样以固定的速度旋转，检测器捕捉穿过煤样试件的X射线，以电信号的形式储存CT扫描图像。
进一步的，步骤B中煤样试件的干燥具体是将煤样试件在室温条件下抽真空24h，然后放入干燥箱内干燥至恒重后称量煤样试件的干重。
更进一步的，划分饱和水浸湿煤样试件的位置具体是每隔8-15mm的间距划分确定饱和水浸湿煤样试件的位置，从煤样试件的一端起按照划分的饱和水浸湿煤样试件位置依次分步进行浸水饱和处理。
还进一步的，步骤C中采用多维核磁共振分析仪进行核磁共振实验，设置间距为5mm截取多层圆形截面和矩形截面。
还进一步的，步骤D中多维核磁共振分析仪还测量煤样试件的驰豫分布和驰豫时间用于制作三维T 2图谱。
发明的有益效果
有益效果
本发明的有益效果是，利用CT扫描仪对煤样试件进行扫描，得到具有各煤层孔裂隙结构的CT扫描图像，再通过多维核磁共振分析仪扫描同一煤样试件，得到三维T 2图谱及含水信号图；结合核磁共振设备具有的分层成像技术，从煤柱的任意方向截取煤岩体的截面，得到任意层面的水分分布情况，从而可以观测核磁共振由于截取截面精度限制而不能观测到的煤体孔裂隙结构，并与核磁共振图谱进行对比，进而全程可视化分析煤体孔裂隙渗流的动态过程，实现煤体动态渗流全程的可视化。
对附图的简要说明
附图说明
图1是煤样试件示意图；
图2是煤样试件饱和水浸湿的位置划分示意图；
图3是煤样试件的截面选取示意图；
图4是实施例2中的三维T 2图谱和含水信号图；
图5是实施例2中的煤样试件的孔裂隙结构示意图。
发明实施例
本发明的实施方式
结合图1至图5所示，本发明提供的一种实现煤体孔裂隙动态渗流过程可视化的方法具体实施方式如下。
煤体中微裂隙(孔隙-裂隙)的存在一方面增加了储层中阻力较小的渗流通道，影响储层渗透率，另外在孔裂隙中局部压力场和流场的变化，导致流体优先通过微裂隙渗流，通过现有的实验手段难以获取的孔裂隙的基本特征(例如孔隙结构、连通性等)和流体参数(例如流体黏度、密度等)。本发明提供了一种无损动态检测技术，实现了对煤体孔裂隙渗流动态过程可视化的表征和分析。
实施例1
一种实现煤体孔裂隙动态渗流过程可视化的方法，使用具有两级放大技术的Xradia 510 Versa 3D X射线显微镜CT扫描仪对煤样试件进行扫描，得到具有各煤层孔裂隙结构的CT图片；采用MacroMR12-100H-GS型多维核磁共振分析仪扫描同 一煤样试件，得到三维T 2图谱及含水信号图。利用该核磁共振设备具有的分层成像技术，从煤柱的任意方向截取煤岩体的截面，得到任意层面的水分分布情况。结合扫描后的CT图片，可以观测核磁共振由于截取截面精度限制而不能观测到的煤体孔裂隙结构，并与核磁共振图谱进行对比，进而全程可视化分析煤体孔裂隙渗流的动态过程；具体的步骤包括：
步骤A.
制作煤样试件，对煤样试件进行CT扫描得到CT扫描图像。
其中，煤样试件为圆柱体试件，试件的尺寸优选是
Figure PCTCN2019112995-appb-000001
CT扫描过程中扫描电压、扫描功率和视场大小根据X射线稳定性、煤样试件尺寸、煤样试件X射线衰减分数和曝光时间来确定；CT扫描时煤样以固定的速度旋转，检测器捕捉穿过煤样试件的X射线，以电信号的形式储存CT扫描图像。
步骤B.
干燥煤样试件至恒重，并划分饱和水浸湿煤样试件的位置，按照位置划分逐段进行抽真空饱和水处理。
其中，煤样试件的干燥具体是将煤样试件在室温条件下抽真空24h，然后放入干燥箱内干燥至恒重后称量煤样试件的干重，可以设置干燥温度为60℃。划分饱和水浸湿煤样试件的位置，具体是每隔8-15mm的间距划分确定饱和水浸湿煤样试件的位置，另外还可以以更小的间距，划分更多的位置从而提高试验的精度；从煤样试件的一端起按照划分的饱和水浸湿煤样试件位置依次分步进行浸水饱和处理，可以按照自下至上的顺序进行，每个位置饱和完成后均进行低场核磁共振测量。
步骤C.
对煤样试件进行核磁共振实验，从任意方向对煤样试件等间距截取多层截面，确定多个方向及多个截面的水分分布。
其中，采用MacroMR12-100H-GS型多维核磁共振分析仪进行核磁共振实验，为了得到不同方向及不同层面的水分分布，可以设置间距为5mm截取多层圆形截面和矩形截面。
步骤D.
观测划分饱和水浸湿煤样试件的各个位置，结合各个截面的水分分布，得到三维T 2图谱和含水信号图。
其中，多维核磁共振分析仪还测量煤样试件的驰豫分布和驰豫时间用于制作三维T 2图谱。
步骤E.
观测煤样试件的孔裂隙结构，分析渗流动态过程。结合CT扫描后的煤体孔裂隙结构图，弥补由于核磁共振截取截面精度限制而不能观测到的煤体孔裂隙结构的缺陷，进而全程分析渗流的动态过程。
上述方法首先利用CT扫描仪对煤样试件进行扫描，得到具有各煤层孔裂隙结构的CT扫描图像，再通过多维核磁共振分析仪扫描同一煤样试件，得到三维T 2图谱及含水信号图；结合核磁共振设备具有的分层成像技术，从煤柱的任意方向截取煤岩体的截面，得到任意层面的水分分布情况，从而可以观测核磁共振由于截取截面精度限制而不能观测到的煤体孔裂隙结构，并与核磁共振图谱进行对比，进而全程可视化分析煤体孔裂隙渗流的动态过程，实现煤体动态渗流全程的可视化。
实施例2
以唐口煤矿气煤制作的煤样试件为例，结合示意图1-5，对本方法的原理及有益效果做进一步的说明。
基于CT扫描和核磁共振技术研究煤体孔裂隙结构渗流动态过程的方法，能够弥补其他方法的局限性，且仅利用核磁共振T 2图谱不能研究动态渗流过程的不足，实现煤体孔裂隙动态渗流过程可视化的方法，使用具有两级放大技术的Xradia510Versa3D X射线显微镜CT扫描仪对煤样试件进行扫描，得到具有各煤层孔裂隙结构的CT扫描图片。采用MacroMR12-150H-I型核磁共振成像分析仪扫描同一煤样试件，得到三维T 2图谱及含水信号图。利用该核磁共振设备具有的分层成像技术，从煤柱的任意方向截取煤岩体的截面，得到任意层面的水分分布情况。结合扫描后的CT图片，观测核磁共振由于截取截面精度限制而不能观测到的煤体孔裂隙结构，并与核磁共振T 2图谱和水分分布图进行对比，进而全程可视化分析煤体孔裂隙渗流的动态过程。
步骤A.在CT扫描试验前，将唐口煤样试件制作成尺寸为
Figure PCTCN2019112995-appb-000002
的煤柱，如图1所示。使用具有两级放大技术的Xradia 510 Versa 3D X射线显微镜CT扫描仪煤样，根据X射线稳定性、样品尺寸、样品的X射线衰减分数、曝光时间等因素的影响，选择扫描电压为65KV，功率为6W，视场大小为12.5×12.5mm 2的实验条件。扫描时煤样以恒定的扫描速度旋转，X射线穿过试样后由检测器进行捕捉，以电信号的形式进行储存并形成CT图像。
步骤B，将煤样试件在室温下抽真空24h，放入60℃干燥箱内干燥至恒重后称量样品干重，以去除样品中的残留水分。
从煤样试件底部起每10mm划分一次饱和水浸湿煤样的位置，并根据划分的浸湿煤样的位置，由低位向高位置逐一进行5次抽真空饱和水处理，如图2所示，每个位置的饱和完成后进行低场核磁共振测试。
步骤C.采用MacroMR12-100H-GS型多维核磁共振分析仪，对经过CT扫描后的煤样进行试验。氢测试探头线圈为25mm自屏蔽线圈，磁体强度0.3T，磁体温度为32±0.01℃。
利用该核磁共振设备的分层成像技术，沿煤样试件截面的横向，由上至下分层截取各小间距为5mm的各层圆形截面，并对该煤样试件沿4个不同方向纵向分层，得到矩形截面的水分分布图，为了避免分层位置对孔裂隙分布的实验结果的影响，可根据孔裂隙实际分布情况在不同位置对煤样进行纵向分割。通过观测设置的饱和水浸湿的不同煤样位置和不同截面，由此实时观测煤层水流入孔隙的水分分布，煤样试件截面选取示意图如图3所示。
步骤D.通过观测设置的饱和水浸湿的不同煤样试件位置和不同截面的水分分布，并结合核磁共振实验得到的三维T 2图谱(高度，弛豫时间，信号量)和含水信号图，由此判断孔裂隙结构及水可以流到的位置，实时观测水流入孔隙的动态过程，任意层面的水分分布及分层含水信号示意图如图4所示。
步骤E.由于该核磁共振的分层成像技术精度有限，各煤层小于1mm间的孔裂隙情况无法观测。结合CT扫描后的煤体孔裂隙结构图，如图5所示，弥补由于核磁共振截取截面精度限制而不能观测到的煤体孔裂隙结构的缺陷，进而可以全程分析渗流的动态过程。
当然，上述说明并非是对本发明的限制，本发明也并不仅限于上述举例，本技术领域的技术人员在本发明的实质范围内所做出的变化、改型、添加或替换，也应属于本发明的保护范围。

Claims (6)

  1. 一种实现煤体孔裂隙动态渗流过程可视化的方法，其特征在于，步骤包括：
    步骤A.制作煤样试件，对煤样试件进行CT扫描得到CT扫描图像；
    步骤B.干燥煤样试件至恒重，并划分饱和水浸湿煤样试件的位置，按照位置划分逐段进行抽真空饱和水处理；
    步骤C.对煤样试件进行核磁共振实验，从任意方向对煤样试件等间距截取多层截面，确定多个方向及多个截面的水分分布；
    步骤D.观测划分饱和水浸湿煤样试件的各个位置，结合各个截面的水分分布，得到三维T 2图谱和含水信号图；
    步骤E.观测煤样试件的孔裂隙结构，分析渗流动态过程。
  2. 根据权利要求1所述的一种实现煤体孔裂隙动态渗流过程可视化的方法，其特征在于，所述步骤A中煤样试件为圆柱体试件，CT扫描过程中扫描电压、扫描功率和视场大小根据X射线稳定性、煤样试件尺寸、煤样试件X射线衰减分数和曝光时间来确定；CT扫描时煤样以固定的速度旋转，检测器捕捉穿过煤样试件的X射线，以电信号的形式储存CT扫描图像。
  3. 根据权利要求1所述的一种实现煤体孔裂隙动态渗流过程可视化的方法，其特征在于，所述步骤B中煤样试件的干燥具体是将煤样试件在室温条件下抽真空24h，然后放入干燥箱内干燥至恒重后称量煤样试件的干重。
  4. 根据权利要求3所述的一种实现煤体孔裂隙动态渗流过程可视化的方法，其特征在于，所述划分饱和水浸湿煤样试件的位置具体是每隔8-15mm的间距划分确定饱和水浸湿煤样试件的位置，从煤样试件的一端起按照划分的饱和水浸湿煤样试件位置依次分步进行浸水饱和处理。
  5. 根据权利要求1所述的一种实现煤体孔裂隙动态渗流过程可视化的方法，其特征在于，所述步骤C中采用多维核磁共振分析仪进行核 磁共振实验，设置间距为5mm截取多层圆形截面和矩形截面。
  6. 根据权利要求5所述的一种实现煤体孔裂隙动态渗流过程可视化的方法，其特征在于，所述步骤D中多维核磁共振分析仪还测量煤样试件的驰豫分布和驰豫时间用于制作三维T 2图谱。
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